1. Field of the Invention
The invention relates to an apparatus for generating ozone by an electric discharge, with a tube ozonizer consisting of a first tubular electrode and a second likewise tubular electrode which is provided with a dielectric layer which faces the first electrode and, between itself and the other electrode, leaves free a cylindrical discharge space through which an oxygen-containing gas can be passed, and also with a supply system consisting of a high-voltage transformer which is fed by low frequency alternating current and the secondary winding of which is connected in parallel both to a storage capacitor and to the series connection of a spark gap and the ozonizer.
2. Description of the Prior Art
Apparatuses of this type for generating ozone have been proposed, for example, in German patent application P 29 34 327.9 or in Swiss patent application No. 7101/79-8.
In addition to the "conventional" feeding of ozonizers with low-frequency alternating current of sine-wave or square-wave form with frequencies between 50 Hz and several kHz, ozone-generating apparatuses operated with pulse-wave currents are becoming increasingly important. Thus, an appliance with rotating electrodes is described in German Offenlegungsschrift 2,652,283. Here, the spark discharge is produced by bringing the rotating electrodes of the spark gap nearer to fixed electrodes. In this case, the spark-gap electrodes are connected to the current supply by means of sliding contacts. German patent application P 29 49 501.0 or Swiss patent application 9753/79-6 also proposes an apparatus for generating ozone, in which the ozonizer is fed via rotating spark gaps.
However, to meet the requirements for a long life and operating safety, the aim is to replace rotating spark gaps by purely electrical/electronic designs. The proposal in the patent applications mentioned above as directed toward this purely electrical design. In order, to generate ozone, a cylindrical discharge channel is subjected to a low-frequency electrical alternating-voltage signal which consists of a sine-wave voltage with positive and negative peak values below the starting voltage of the ozonizer and of voltage pulses which are superimposed on the sine-wave voltage essentially at its maximum and minimum values to form a voltage increase leading to arc-through in the ozonizer. Among other things, a spark gap preferably integrated in the ozonizer is used as a switching element for the arc-through of the pulses.